Semiconductor device fabrication is a process used to create integrated circuits that are present in everyday electrical and electronic devices. The fabrication process is a multiple-step sequence of photolithographic and chemical processing steps during which electronic circuits are gradually created on a wafer composed of a semiconducting material.
Electronic circuits can interfere with adjacent circuits by leaking current or charge into the adjacent devices. One technique to mitigate this leakage is by forming isolation structures between the adjacent devices. The isolation structures are typically formed prior to forming the integrated circuits, such as transistors.
One type of isolation structure is a shallow trench isolation (STI) structure. Typically, the STI structure is formed by forming a shallow trench in a silicon substrate. The trench is filled with silicon dioxide. Then, a chemical mechanical planarization process is used to remove excess silicon dioxide. Then, integrated circuits, such as transistors, are formed and leakage between adjacent circuits is mitigated by the STI structure.